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The design and on-sky results of the prototype of a low-resolution spectrograph for the thai national telescope
(2020-01-01)
Paenoi, Jitsupa
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Buisset, Christophe
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Suwansukho, Kajpanya
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Sirichote, Wichit
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Choochalerm, Piyamas
The objectives of the research project presented in this paper are to design and develop a Low Resolution Spectrograph for the 2.4 m Thai National Telescope. The Low Resolution Spectrograph will deliver a spectrum in the spectral range (440-740 nm), with a resolution of R approximately equals to 1,000 at the central wavelength, λ<inf>c,</inf> of 600 nm, while observing through a slit with a width of 0. 9 arcsecond wide (in long-slit mode) or during slit-less observations. The Low Resolution Spectrograph was designed to have a total weight of less than 20 kg and a maximum displacement due to gravity of less than 6 microns during a 360° rotation of the instrument cube. We have installed a prototype of the Low Resolution Spectrograph on the Thai National Telescope in December 2018. We have tested its performance on stellar objects during a one-night observing run. During these observations we calibrated the instrument using a Thorium-Argon spectral calibration lamp and a Tungsten lamp and recorded the spectrum of the planetary nebula NGC 2392 in both slit-less and long-slit modes. We measured a spectral resolution of 800-1,300 over the wavelength range 440-740nm, thus demonstrating that the on-sky performance of the prototype was in agreement with the theoretical specifications.
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A simplified and powerful image processing methods to separate Thai jasmine rice and sticky rice varieties
(2018-01-01)
Khondok, Piyoros
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Sakulkalavek, Aparporn
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Suwansukho, Kajpanya
A simplified and powerful image processing procedures to separate the paddy of KHAW DOK MALI 105 or Thai jasmine rice and the paddy of sticky rice RD6 varieties were proposed. The procedures consist of image thresholding, image chain coding and curve fitting using polynomial function. From the fitting, three parameters of each variety, perimeters, area, and eccentricity, were calculated. Finally, the overall parameters were determined by using principal component analysis. The result shown that these procedures can be significantly separate both varieties.
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Activity status and future plans for the Optical Laboratory of the National Astronomical Research Institute of Thailand
(2018-01-01)
Buisset, Christophe
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Poshyachinda, Saran
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Soonthornthum, Boonrucksar
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Prasit, Apirat
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Alagao, Mary Angelie
The National Astronomical Research Institute of Thailand (NARIT) has developed since June 2014 an optical laboratory that comprises all the activities and facilities related to the research and development of new instruments in the following areas: Telescope design, high dynamic and high resolution imaging systems and spectrographs. The facilities include ZEMAX and Solidwork software for design and simulation activities as well as an optical room with all the equipment required to develop optical setup with cutting-edge performance. The current projects include: I) the development of a focal reducer for the 2.3 m Thai National Telescope (TNT), ii) the development of the Evanescent Wave Coronagraph dedicated to the high contrast observations of star close environment and iii) the development of low resolution spectrographs for the Thai National Telescope and for the 0.7 m telescopes of NARIT regional observatories. In each project, our activities start from the instrument optical and mechanical design to the simulation of the performance, the development of the prototype and finally to the final system integration, alignment and tests. Most of the mechanical parts are manufactured by using the facilities of NARIT precision mechanical workshop that includes a 3-axis Computer Numerical Control (CNC) to machine the mechanical structures and a Coordinate Measuring Machine (CMM) to verify the dimensions. In this paper, we give an overview of the optical laboratory activities and of the associated facilities. We also describe the objective of the current projects, present the specifications and the design of the instruments and establish the status of development and we present our future plans.
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Changes in structural, morphological, and corrosion properties of CrN thin film effected by varying N2 pressure In the sputtering process
(2015-01-01)
Wongtanasarasin, Wichuda
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Sakdanuphab, Rachsak
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Suwansukho, Kajpanya
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Sakulkalavek, Aparporn
In this study, we investigate a facet of the fabrication process of chromium nitride (CrN) film intended as a protective coating for pineapple blades. CrN thin films were deposited on unpolished stainless steel substrates (AISI304) by DC reactive magnetron sputtering in Ar+N<inf>2</inf> gases. In principle, the proportion of nitrogen partial pressure to the total pressure in the sputtering process should have considerable effects on the CrN film's chemical composition, its crystal structure, its hardness, and its corrosion resistance. We tested this supposition out by using several different nitrogen partial pressures in the sputtering process and observed the films deposited. The coatings were deposited at five different nitrogen partial pressures of 4.0×10-4 mbar, 8.0×10-4 mbar, 1.2×10-3 mbar, 1.6×10-3 mbar, and 2.0×10-3. The deposition times were controlled to achieve 5-μm thick films in each deposition. The films were analyzed by several analytical methods, such as X-ray diffraction (XRD), scanning electron microscope, micro-hardness and potentiostat in pineapple juice. The XRD spectra of the films showed face-centered cubic structure with (200) preferred orientation, positively identifying them as Cr<inf>2</inf>N and CrN thin films. The calculated d-spacing and lattice parameter of the CrN films increased with increasing nitrogen partial pressure; the ranges were 0.283-0.287 nm and 0.491-0.497 nm, respectively. The cross-section morphology of the CrN films reveals the columnar grain growth with a high density. The crystal structure and the grain texture correspond with the hardness property. The films corrosion potential, an indicator of their corrosion property, was varied from -0.14 to -0.05 volts with varying nitrogen pressure. The most corrosion resistant and the good hardness were the film fabricated at the nitrogen partial pressure of 1.2×10-3 mbar.
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Fast fluorescent imaging-based Thai jasmine rice identification with polynomial fitting function and neural network analysis
(2014-04-01)
Suwansukho, Kajpanya
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Sumriddetchkajorn, Sarun
;
Buranasiri, Prathan
With our single-wavelength spectral-imaging-based Thai jasmine rice identification system, we emphasize here that a combination of an appropriate polynomial fitting function on the determined chain code and a well-trained neural network configuration is highly sufficient in achieving a low false acceptance rate (FAR) and a low false rejection rate (FRR). Experimental demonstration shows promising results in identifying our desired Thai jasmine rice from six unwanted rice varieties with FAR and FRR values of 6.2% and 7.1%, respectively. Additional key performances include a much faster identification time of 30.5 s, chemical-free analysis, robustness, and adaptive learning.
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Single-wavelength based thai jasmine rice identification with polynomial fitting function and neural network analysis
(2013-09-18)
Suwansukho, Kajpanya
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Sumriddetchkajorn, Sarun
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Buranasiri, Prathan
We previously showed that a combination of image thresholding, chain coding, elliptic Fourier descriptors, and artificial neural network analysis provided a low false acceptance rate (FAR) and a false rejection rate (FRR) of 11.0% and 19.0%, respectively, in identify Thai jasmine rice from three unwanted rice varieties. In this work, we highlight that only a polynomial function fitting on the determined chain code and the neural network analysis are highly sufficient in obtaining a very low FAR of < 3.0% and a very low 0.3% FRR for the separation of Thai jasmine rice from Chainat 1 (CNT1), Prathumtani 1 (PTT1), and Hom-Pitsanulok (HPSL) rice varieties. With this proposed approach, the analytical time is tremendously suppressed from 4,250 seconds down to 2 seconds, implying extremely high potential in practical deployment. © 2013 SPIE.
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Improvement of single wavelength-based Thai jasmine rice identification with elliptic Fourier descriptor and neural network analysis
(2012-12-01)
Suwansukho, Kajpanya
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Sumriddetchkajorn, Sarun
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Buranasiri, Prathan
Instead of considering only the amount of fluorescent signal spatially distributed on the image of milled rice grains this paper shows how our single-wavelength spectral-imaging-based Thai jasmine (KDML105) rice identification system can be improved by analyzing the shape and size of the image of each milled rice variety especially during the image threshold operation. The image of each milled rice variety is expressed as chain codes and elliptic Fourier coefficients. After that, a feed-forward back-propagation neural network model is applied, resulting in an improved average FAR of 11.0% and FRR of 19.0% in identifying KDML105 milled rice from the unwanted four milled rice varieties. © Copyright SPIE.
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Demonstration of a single-wavelength spectral-imaging-based Thai jasmine rice identification
(2011-07-20)
Suwansukho, Kajpanya
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Sumriddetchkajorn, Sarun
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Buranasiri, Prathan
A single-wavelength spectral-imaging-based Thai jasmine rice breed identification is demonstrated. Our nondestructive identification approach relies on a combination of fluorescent imaging and simple image processing techniques. Especially, we apply simple image thresholding, blob filtering, and image subtracting processes to either a 545 or a 575nm image in order to identify our desired Thai jasmine rice breed from others. Other key advantages include no waste product and fast identification time. In our demonstration, UVC light is used as our exciting light, a liquid crystal tunable optical filter is used as our wavelength seclector, and a digital camera with 640 active pixels × 480 active pixels is used to capture the desired spectral image. Eight Thai rice breeds having similar size and shape are tested. Our experimental proof of concept shows that by suitably applying image thresholding, blob filtering, and image subtracting processes to the selected fluorescent image, the Thai jasmine rice breed can be identified with measured false acceptance rates of <22:9% and <25:7% for spectral images at 545 and 575nm wavelengths, respectively. A measured fast identification time is 25ms, showing high potential for real-time applications. © 2011 Optical Society of America.
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Identification of Thai hom mali rice using a refractometer
(2009-09-08)
Sumriddetchkajorn, Sarun
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Suwansukho, Kajpanya
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Buranasiri, Prathan
Because Thai Hom Mali, also known as Thai Dawk Mali (KDML105), rice is very popular and its price is high compared to other Thai rice varieties, there is an increase in mixing KDML105 milled and unmilled rice grains with other rice varieties, leading to unqualified KDML105 milled rice products for export and unqualified KDML105 unmilled rice seeds for next plants. Instead of using traditional time- and energy- consuming procedures such as alkaline spreading value and pasting property tests, this paper proposes a fast refractometry-based method to analyze ground milled rice grains dissolved in an alkaline solution. Our idea comes from the fact that due to differences in the amount of amylose content in each rice variety, the refractive index of the milled rice powder dissolved in an alkaline solution can be used to distinguish the desired KDML105 rice from others. In our approach, only 0.1 grams of milled rice powder is ground, it is then dissolved in a 10% potassium hydroxide, and its refractive index is investigated. Our experiment using a temperature-controlled optical refractometer and four Thai rice varieties (KDML105, Pathumthani1, Chainat1, and a Thai sticky rice) shows that the milled KDML105 rice can be distinguished from the remaining three rice varieties with a total false error rate of 6.7% and the required measurement time of < 20 seconds. Key advantages include simplicity, moderate accuracy, and less waste produced. © 2009 SPIE.

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